1. Field of the Invention
The present invention relates to the structure of the connection of an end of a flexible tube, serving as an element of a treatment tool used for an endoscope, with a mouthpiece serving as an element of the same treatment tool.
2. Description of the Related Art
FIG. 1 shows the structure of the connection of one end (connecting end) of a flexible tube 90 (e.g., a flexible sheath which sheathes a flexible metal tube (not shown)) with a mouthpiece 91. The flexible tube 90 and the mouthpiece 91 are elements of a conventional treatment tool used for an endoscope. The mouthpiece 91 is provided at the rear end thereof with a cylindrical connecting portion 92 having self-locking spiral claw projections 93 formed around the cylindrical connecting portion 92. The outer edges of the self-locking spiral claw projections 93 are formed sharp in order to prevent the connecting end of the flexible tube 90 from coming off the cylindrical connecting portion 92. The connecting end of the flexible tube 90 is press-fitted snugly onto the cylindrical connecting portion 92 so as to be engaged with the spiral claw projection 93. This connecting structure is disclosed in, e.g., Japanese Utility Model No. 2,517,159.
The spiral claw projections 93 are formed as a single continuous spiral male thread-like projection. Accordingly, the flexible tube 90 cannot be fixed to the cylindrical connecting portion 92 securely even if the connecting end of the flexible tube 90 is press-fitted snugly onto the cylindrical connecting portion 92 (or even if the connecting end of the flexible tube 90 is screwed snugly on the cylindrical connecting portion 92) because the spiral claw projections 93 only slightly dig into the inner peripheral surface of the connecting end of the flexible tube 90.
For this reason, in such a conventional connecting structure, in order to firmly fix the connecting end of the flexible tube 90 with the cylindrical connecting portion 92, a cord 94 has to be wrapped around the connecting end of the flexible tube 90 tightly to reinforce the connection between the connecting end of the flexible tube 90 and the cylindrical connecting portion 92. However, there is a possibility of the cord 94 loosening when the treatment tool is in operation. If the cord 94 loosens when the treatment tool is in operation, the mouthpiece may rotate about the axis thereof relative to the flexible tube 90 and finally come off the connecting end of flexible tube 90. Furthermore, since the spiral claw projection 93 cannot deeply dig into the inner peripheral surface of the connecting end of the flexible tube 90, the outer diameter of the connecting end of the flexible tube 90 at this portion becomes undesirably larger than that of the other portion of the flexible tube 90.
It is an object of the present invention to provide a connecting structure of a flexible tube of a treatment tool used for an endoscope with a mouthpiece of the same treatment tool, wherein the flexible tube is securely connected with the mouthpiece without increasing the outer diameter of the connecting end of the flexible tube.
To achieve the object mentioned above, according to the present invention, a connecting structure for a flexible tube and a mouthpiece is provided, the flexible tube and the mouthpiece serving as elements of a treatment tool for an endoscope, the connecting structure including at least one claw projection provided on an outer peripheral surface of a cylindrical connecting portion of the mouthpiece; and at least one claw-projection gap provided on the outer peripheral surface of the cylindrical connecting portion of the mouthpiece at a discontinuous portion of each corresponding the at least one claw projection. A connecting end of the flexible tube is inserted onto the cylindrical connecting portion so that the at least one claw projection digs into an inner peripheral surface of the connecting end of the flexible tube. Each of the at least one claw projection is provided on the outer peripheral surface of the cylindrical connecting portion of the mouthpiece on a plane perpendicular to an axis of the cylindrical connecting portion. A surface of each claw projection, which is in press-contact with the inner peripheral surface of the connecting end of the flexible tube, is inclined inward, toward the outer peripheral surface of the cylindrical connecting portion, in a direction so as to allow the cylindrical connecting portion to be inserted into the connecting end of the flexible tube.
Preferably, each of the at least one claw projection is formed to have a C-shape in cross section taken along a plane normal to the axis of the cylindrical connecting portion.
Preferably, the surface of each claw projection is inclined toward the outer peripheral surface of the cylindrical connecting portion in a direction opposite to the direction of insertion of the flexible tube onto the cylindrical connecting portion.
In an embodiment, each of the flexible tube and the mouthpiece serves as an element of a spray device for an endoscope.
In an embodiment, each of the at least one claw projection includes another surface which functions to prevent the connecting end of the flexible tube from coming off the cylindrical connecting portion of the mouthpiece, and wherein an angle of the another surface relative to the outer peripheral surface of the cylindrical connecting portion is 90 degrees.
In an embodiment, each of the at least one claw projection includes another surface which functions to prevent the connecting end of the flexible tube from coming off the cylindrical connecting portion of the mouthpiece, and wherein an angle of the another surface relative to the outer peripheral surface of the cylindrical connecting portion 11a is less than 90 degrees.
According to another aspect of the present invention, a spray device used for an endoscope is provided, the spray device having a liquid-transfer tube and a spray nozzle connected to a distal end of the liquid-transfer tube, the spray nozzle including at least one spiral guide channel provided in front of the distal end of the liquid-transfer tube; a liquid whirling chamber provided in front of the at least one spiral guide channel to be connected to an outlet thereof; an orifice formed at a center of a front inner surface of the liquid whirling chamber, wherein liquid is transmitted to the liquid whirling chamber via the liquid-transfer tube and the at least one spiral guide channel spurting from the orifice in the form of a spray; at least one claw projection provided on an outer peripheral surface of a cylindrical connecting portion formed at the rear end of the spray device; and at least one claw-projection gap provided on the outer peripheral surface of the cylindrical connecting portion at a discontinuous portion of a corresponding one of the at least one claw projection. The distal end of the liquid-transfer tube is inserted onto the cylindrical connecting portion so that the at least one claw projection digs into an inner peripheral surface of the connecting end of the liquid-transfer tube. Each of the at least one claw projection is provided on the outer peripheral surface of the cylindrical connecting portion on a plane perpendicular to an axis of the cylindrical connecting portion. A surface of each claw projection, which is in press-contact with the inner peripheral surface of the connecting end of the liquid-transfer tube, is inclined inward, toward the outer peripheral surface of the cylindrical connecting portion, in a direction so as to allow the cylindrical connecting portion to be inserted into the connecting end of the liquid-transfer tube.
According to another aspect of the present invention, a mouthpiece to be inserted into an open end of a flexible tube is provided, including a cylindrical connecting portion to be contacted to an inner cylindrical surface of the open end of the flexible tube; and at least one sector claw projection provided, on a common plane perpendicular to the axis of the cylindrical connecting portion, on the outer peripheral surface of the cylindrical connecting portion so that at least one claw-projection gap is provided between the sector claw projection. A cross section, in an axial direction of the cylindrical connection portion, of the sector claw projection defines a knife edge so that the outer peripheral tip end thereof digs into the inner cylindrical surface of the flexible tube.
Preferably, the knife edge includes a leading surface that is inclined relative to normal plane to the axis of the cylindrical portion and trailing surface that is substantially normal to the axis.
The mouthpiece and the flexible tube can serve as elements of a treatment tool for an endoscope.
In an embodiment, a plurality of the at least one sector claw projection and corresponding the at least one claw-projection gap are provided at different positions with respect to the axis of the cylindrical connecting portion.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 11-324935 (filed on Nov. 16, 1999) which is expressly incorporated herein by reference in its entirety.